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380
Checking Operations of CQM1 Master Units
Section 6-4
The Master Unit’s RD
indicator is OFF
The communications cable is not connected
to the Master.
Connect the communications cable correctly.
One of the Slaves is not turned ON.
(The Slave’s PWR indicator is OFF.)
Turn ON the Slave’s power supply.
There is a problem with the Slaves’ power
supply.
Check the power supply cable connections and
connect the cables to the Slaves correctly.
The Slaves’ power supply is inadequate.
Check the power supply capacity. If it is inade-
quate, either change the system configuration or
change the power supply so that sufficient power
is provided.
There is a problem with the communication
cable connection or the cable itself.
Check the connections and cable. Replace the
communications cable if it is faulty.
Communications modes of Master Unit and
Slave do not match.
Set the communications mode so that it is the
same as that of the Master Unit.
A common system mistake has been made.
(Refer to the table on page 382 for a list of
common mistakes.)
Refer to the table on page 382 for common mis-
takes and their remedies.
The Master Unit or a Slave Unit is faulty.
Replace the Master Unit. Replace the Slave Units
if the problem recurs.
The Master Unit’s ERS
indicator is ON
The same area may be allocated to more
than one Slave.
Either change the Slaves’ node number settings to
eliminate the I/O Area overlap or change the Mas-
ter Unit’s “number of points/node number” setting
to 8-point mode by turning pin 3 of the DIP switch
OFF. Turn the PLC ON again after making the
necessary changes.
The PLC’s data area has been exceeded.
Either change the node number setting of the
Slave that exceeded the PLC’s I/O Area or change
the Master Unit’s “number of points/node number”
setting to 8-point mode by turning pin 3 of the DIP
switch OFF. Turn the PLC ON again after making
the necessary changes.
A 16-point or greater Slave has been con-
nected even though the Master Unit’s num-
ber of points/node number setting is 4-point
mode. (Pin 3 of the DIP switch is ON.)
Either remove the 16-point or greater Slave or
change the Master Unit’s number of points/node
number setting to 8-point mode by turning pin 3 of
the DIP switch OFF. Turn the PLC ON again after
making the necessary changes.
There is a problem with the communication
cable connection or the cable itself.
Check the connections and cable. Replace the
communications cable if it is faulty.
A Slave Unit is faulty.
Replace the faulty Slave Unit.
The Master Unit’s ERS
indicator is flashing
The “PLC word allocation” setting is 2 or 4
words, but an out-of-range node number
from 0 to 7 has been set.
(An address over error occurred.)
Either remove the Slave where the error occurred
or change the Master’s PLC word allocation set-
ting (pins 1 and 2) and max. number of Slaves set-
ting (pin 3) so that the Slave’s node number is
acceptable.
Refer to
for a table showing
all of the possible DIP switch settings.
A Slave Unit is faulty.
Replace the faulty Slave Unit.
Error
Probable cause
Possible remedy